It is known to maintain high fluid pressures, necessary to close a frictional engagement device, such as a wet clutch, during the closed operation of the device. Unfortunately, it requires energy to maintain the high pressures. For example, operating a fluid pump at high pressure to maintain a wet clutch in a transmission in a closed position can increase fuel consumption for a vehicle housing the transmission by 4-7%. Commonly owned U.S. Provisional Patent Application 60/936,348, filed Jun. 20, 2007, discloses a spring and wedge arrangement for blocking a fluid chamber to reduce the fluid pressure required from a pump supplying fluid for the chamber. This arrangement could be improved by decreasing the time lag between operating states for a clutch or other device using the arrangement. U.S. Pat. No. 5,125,323 (Yonezawa) discloses a check valve arrangement for feeding a hydraulic chamber. Unfortunately, Yonezawa does not disclose a mechanism to account for the undesirable loss of fluid from the chamber through the check valve as the check valve changes from an open position to a closed position. Yonezawa also discloses an undesirably complex arrangement for adjusting pressure in the chamber once the check valve is fully closed.
Thus, there is a long-felt need for an arrangement to reduce the fluid pressure necessary to maintain a frictional engagement device, such as a wet clutch, in a closed position, while compensating for undesired fluid exchange occurring during the closing of the frictional engagement device.